The present invention relates to a scroll compressor.
Japanese Unexamined Patent Application Publication No. 2004-301091 discloses a conventional scroll compressor including a housing, a fixed scroll and a movable scroll. The housing has therein a discharge pressure region, a compression pressure region and a suction pressure region. The fixed scroll is fixed in the housing to form a discharge chamber which functions as the discharge pressure region. The movable scroll cooperates with the fixed scroll to form therebetween a compression chamber which functions as the compression pressure region. An oil separator is fixed in the discharge pressure region to form an oil separation chamber. The discharge pressure region is formed by the discharge chamber and the oil separation chamber. The oil separation chamber serves to separate lubricating oil from refrigerant gas discharged from the compression chamber and to store the separated lubricating oil.
The scroll compressor further includes a fixed block and an elastic plate. The fixed block is fixed in the housing to form a suction chamber which functions as the suction pressure region. The fixed block cooperates with the movable scroll to form therebetween a backpressure chamber which functions as the compression pressure region. The elastic plate is flat, annular and held between the peripheral wall of the fixed scroll and the fixed block. The elastic plate is in sliding contact with the movable scroll.
The backpressure chamber and the oil separation chamber are connected by an oil supply passage. The oil supply passage has a flow restrictor that is in the form of a slit formed through the elastic plate, extending in an arcuate shape between the peripheral wall of the fixed scroll and the fixed block. The flow restrictor is made to have a small cross-sectional area.
With an orbital motion of the movable scroll, the compression chamber is moved radially inward while reducing its volume. Refrigerant gas in the suction chamber is introduced into the compression chamber for compression and then discharged into the discharge chamber. Lubricating oil contained in the refrigerant gas is separated in the oil separation chamber and stored therein. The separated lubricating oil is moved through the oil supply passage to the backpressure chamber and serves to increase the pressure of the backpressure chamber. As a result, the movable scroll is urged toward the fixed scroll by elasticity of the elastic plate and the pressure of the backpressure chamber so that the compression chamber is appropriately sealed.
The lubricating oil having been moved through the oil supply passage to the backpressure chamber is returned to the suction chamber and used for lubrication of components such as an electric motor provided in the suction chamber. In this case, the flow restrictor formed in the elastic plate is filled with lubricating oil, which serves to prevent the flow of refrigerant gas through the oil supply passage, resulting in reduced power loss of the scroll compressor caused by the flow of refrigerant gas between the backpressure chamber and the oil separation chamber of discharge pressure through the oil supply passage.
In the above-described scroll compressor in which the flow restrictor is provided in the elastic plate, the cross-sectional area of the flow restrictor is not necessarily small enough to reduce the power loss of the compressor. However, forming the flow restrictor of a smaller cross-sectional area in the elastic plate by press requires higher accuracy, which reduces productivity of the scroll compressor and makes it difficult to reduce its manufacturing cost.
The present invention is directed to providing a scroll compressor that allows reduced manufacturing cost and reduced power loss.